There are only few approaches, which confer a resistance to pathogens, mainly fungal pathogens, to plants. This shortcoming can partly be attributed to the complexity of the biological systems in question. Another fact which stands in the way of obtaining resistances to pathogens is that little is known about the interactions between pathogen and plant. The large number of different pathogens, the infection mechanisms developed by these organisms and the defence mechanisms developed by the plant phyla, families and species interact with one another in many different ways.
Fungal pathogens have developed essentially two infection strategies. Some fungi enter into the host tissue via the stomata (for example rusts, Septoria species, Fusarium species) and penetrate the mesophyll tissue, while others penetrate via the cuticles into the epidermal cells underneath (for example Blumeria species).
The infections caused by the fungal pathogens lead to the activation of the plant's defence mechanisms in the infected plants. Thus, it has been possible to demonstrate that defence reactions against epidermis-penetrating fungi frequently start with the formation of a penetration resistance (formation of papillae, strengthening of the cell wall with callose as the main constituent) underneath the fungal penetration hypha (Elliott et al. Mol Plant Microbe Interact. 15: 1069-77; 2002).
In some cases, however, the plant's defence mechanisms only confer an insufficient protection mechanism against the attack by pathogens.
The formation of a penetration resistance to pathogens whose infection mechanism comprises a penetration of the epidermal cells or of the mesophyll cells is of great importance both for monocotyledonous and for dicotyledonous plants. In contrast to the described mlo-mediated resistance, it can probably make possible the development of a broad-spectrum resistance against obligatory biotrophic, hemibiotrophic and necrotrophic fungi.
The present invention was therefore based on the object of providing a method for generating a resistance of plants to penetrating pathogens.
The object is achieved by the embodiments characterized in the claims.